title: Molecular cloning and expression of ps20 growth inhibitor. A novel WAP-type "four-disulfide core" domain protein expressed in smooth muscle.
abstract: We previously reported the purification of ps20 (Rowley, D. R., Dang, T. D., Larsen, M., Gerdes, M. J., McBride, L., and Lu, B. (1995) J. Biol. Chem. 270, 22058-22065), a urogenital sinus mesenchymal cell secreted protein having growth-inhibitory properties. We report here cloning of the 1.03-kilobase rat ps20 cDNA clone from the PS-1 (adult rat prostate smooth muscle) cDNA library. Partial clones were obtained by nested polymerase chain reaction with degenerate primers, and full-length ps20 cDNA clones were isolated by plaque hybridization. Sequence analysis revealed that ps20 protein contains a WAP-type "four-disulfide core" motif and is a novel member of the WAP signature protein family composed primarily of secreted serine protease inhibitors. Native ps20 immunoprecipitated from smooth muscle cells and recombinant ps20 both resolved on SDS-polyacrylamide gel electrophoresis with apparent molecular mass of 27-29 kDa under reducing conditions and 21-23 kDa under non-reducing conditions, respectively. Stable ps20-transfectant COS-7 cell lines secreted ps20 and were growth-inhibited relative to mock transfectants. In addition, COS-7 and prostate carcinoma PC-3 cells were growth-inhibited by bacterially expressed ps20. Northern analysis indicated differential expression by tissue with highest expression in the heart. Immunohistochemical localization of ps20 protein showed cell-specific expression by both visceral and vascular smooth muscle in all tissues, including the prostate gland. These results indicate ps20 is a novel growth-regulatory member of the WAP signature family expressed by smooth muscle cells.
authors.affiliation: Cell and Molecular Biology Program, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: M
authors.initials: M
authors.lastname: Larsen
authors.forename: S J
authors.initials: SJ
authors.lastname: Ressler
authors.forename: B
authors.initials: B
authors.lastname: Lu
authors.forename: M J
authors.initials: MJ
authors.lastname: Gerdes
authors.forename: L
authors.initials: L
authors.lastname: McBride
authors.forename: T D
authors.initials: TD
authors.lastname: Dang
authors.forename: D R
authors.initials: DR
authors.lastname: Rowley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004220:Disulfides / Q000737:chemistry*; D005260:Female; D006131:Growth Inhibitors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D011506:Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D004220:Disulfides; D006131:Growth Inhibitors; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; C095570:Wfdc1 protein, rat